Modeling for Oyster and Rivers: Presentations at Mississippi Water Resources Conference April 3-4.
Research engineers from Mississippi State University are developing a hydrodynamic and water quality model for the Western Mississippi Sound for MDEQ and the National Fish and Wildlife Foundation (NFWF funding from the BP settlement). The model will be used to identify the most appropriate locations for oyster bed restoration and cultch deployment in the Western Sound. Dr. Medhi Armandei is building this model to simulate flow, salinity, and temperature in a rectangular area 60 X 20 miles stretching between Lake Borgne/ Rigolets, Louisiana and Gulfport, Mississippi. The hydrodynamic model is a driving mechanism for simulating water quality characteristics and nutrient transport. The model divides the area into 4 layers of water, each within a 3000 cell computational grid. The hydrodynamic part of the model is finalized, but the water quality part is still being calibrated. The model outputs are being compared to actual measurements of water surface elevation, temperature and salinity from recording buoys, with acceptably high correlations between modeled and actual data. Because of gaps in water quality data sets containing historical measurements of Mississippi Sound nutrients, such as nitrogen, phosphorous and organic carbon; the calibration of the model on these parameters is not complete yet. After final calibration, the model will be run to simulate extreme stress conditions for oysters, such as an open Bonnet Carre spillway and/or the Pearl River in flood stage. The search for optimal areas of Mississippi Sound bottom to restore with new cultch/hard material for oyster attachment can be refined and focused using this model that will simulate a range of environmental conditions.
In a different conference session, a river modeling project was presented by Dr. Rodney Knight from the United States Geological Survey (USGS). Last year at the Miss. Water Resources Conference, he introduced a project funded by the RESTORE Act Gulf-wide River Flow Study for Pascagoula River flow modeling using OASIS, a software developed by Hydrologics, Inc. This year in Phase II, the Pearl River in Mississippi and Louisiana will be added to the project. Healthy Gulf (then GRN) submitted this modeling idea to the MDEQ restoration project portal in August 2018, and advocated for it to MDEQ, the Louisiana Congressional Delegation, Louisiana Senate, and to the NRDA Trustee Council at their July 2018 annual meeting. We welcome the Pearl River being added to the project in Phase II. OASIS is a mass-balance model that integrates environmental and water discharge data, and is designed to aid management decisions, such as water budgeting - especially on regulated (dammed) rivers like the Pearl. The Miss. Sound and Pearl River modeling studies are related. The Pearl River provides the dominant fresh water input to the Western Mississippi Sound, Lake Borgne and Rigolets, and is important because its flow modifies salinity in important oyster growing areas of Louisiana and Mississippi.